Resistor grid



May 25 1926.

1,586,240 F. T. COPE RESISTOR GRID Filed Dec; 21, 1925 gwuentoo Wis M v Patented May 2 5, 1926.

UNITED STATES PATENT OFFICE.

FRANK COPE, OF SALEM, OHIO, ASSJIGNOR TO THE ELECTRIC FURNACE COMPANY,

' OF SALEM, OHIO, A CORPORATION OF OHIO.

RESISTOR GRID.

Application filed December 21, 1925. Serial No. 76,674.

The invention relates to metallic resistors for electric furnaces and the like, and more 7 particularly to means for changing the resistance of such resistors.

The objects of the improvement are to provide a resistor grid of serpentine shape having connecting webs or shunts between certain loops for normally lowering the resistance, said webs being adapted to be severed or removed to increase the resistance of the grid.

An embodiment of the invention is illustrated in the accompanying drawing, in which a 15 Figure. 1 is an elevation of a pair of resistors embodying the invention located in the relative position in which they are mounted in a furnace or the like, and

Fig. 2, an enlarged fragmentary elevation of a portion of one of the resistors showing the webs severed or removed to increase the resistance.

Similar numeralsof reference indicate corresponding parts throughout the drawmg.

adaptable for use in the side walls, roof or hearth of an electric furnace or the like, and for the purpose of illustration a pair of position in which they may be mounted upon the furnace wall.

When these resistors are installed in a furnace the exact resistance required is not always known and for this purpose certain loo s ed by means of webs cast in the grid. The current will thus pass through these webs and not around. the loops which are The grid or resistor to which the inven Resistorsof this general type are these grids are shown in Figure 1 in'theas indicated at 4 may be short circuit-' thus shunted out, obviouslyreducing the resistance of the grid,

-After the resistors are installed in the furnace and current is applied to the same if it is found that the resistance is not sufflcient, certain of the webs 5' may be severed or removed as indicated at 6 in Fig. 2, thus preventing the current from passing through the web and forcing it to go through the accompanying loop 4, increas-,

loops and provided with webs bridging certain of said loops, said webs being adapted to'be severed to increase the resistance of the resistor.

3. A resistor formed of a plurality of straight portions connected at their ends by curved portions, and provided with webs bridging certain of the straight portions, said webs being adapted to be severed to increase the resistance of the resistor.

4. A resistor formed of a plurality of parallel portions connected at their ends by curved portions, and'provided with Websv bridging certain of the parallel portions, saidwebs being adapted to be severed to increase the resistance of the resistor.

5. A cast resistor grid comprising a plurality of parallel portions connected at alternate ends by curved portions, and integral webs connecting certain pairs of parallel portions adjacent to the curved portions, said webs being adapted to be severed to increase the resistance of the resistor,

6. An electric furnace resistor in which the initial resistance of the resistor as inportions of which are initially shunted, the

stalled is lower than the operating resistshunts being adapted to be removed as ance required for normal operation, and so required to increase the resistance to the 10 constructed that the resistance may be indesired point for normal operation. creased to the desired point by the removal In testimony that I claim the above, I of shunts. have hereunto subscribed my name;

7. An electric furnace resistor, certain FRANK T. COPE. 

